Spontaneous Spin Bifurcations and Ferromagnetic Phase Transitions in a Spinor Exciton-Polariton Condensate
We observe a spontaneous parity breaking bifurcation to a ferromagnetic state in a spatially trapped exciton-polariton condensate. At a critical bifurcation density under nonresonant excitation, the whole condensate spontaneously magnetizes and randomly adopts one of two elliptically polarized (up to 95% circularly polarized) states with opposite handedness of polarization. The magnetized condensate remains stable for […]
Convective Cage Release in Model Colloidal Glasses
The mechanism of flow in glassy materials is interrogated using mechanical spectroscopy applied to model nearly hard sphere colloidal glasses during flow. Superimposing a small amplitude oscillatory motion orthogonal onto steady shear flow makes it possible to directly evaluate the effect of a steady state flow on the out-of-cage (α) relaxation as well as the […]
Tunable Magnetic Alignment between Trapped Exciton-Polariton Condensates
Tunable spin correlations are found to arise between two neighboring trapped exciton-polariton condensates which spin polarize spontaneously. We observe a crossover from an antiferromagnetic to a ferromagnetic pair state by reducing the coupling barrier in real time using control of the imprinted pattern of pump light. Fast optical switching of both condensates is then achieved […]
Lasing in Bose-Fermi mixtures
Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in […]
Nonlinear control of high-frequency phonons in spider silk
Spider dragline silk possesses superior mechanical properties compared with synthetic polymers with similar chemical structure due to its hierarchical structure comprised of partially crystalline oriented nanofibrils. To date, silk’s dynamic mechanical properties have been largely unexplored. Here we report an indirect hypersonic phononic bandgap and an anomalous dispersion of the acoustic-like branch from inelastic (Brillouin) […]
Templated Self-Assembly of Colloidal Nanocrystals into Three-Dimensional Mesoscopic Structures: A Perspective on Synthesis and Catalytic Prospects
Inorganic nanocrystals (NCs) of uniform size are of eminent importance for the fields of catalysis, energy storage and conversion, and electrochemical devices. Current efforts in science of nanoparticles have focused on the propensity of discrete colloidal NCs to assemble into two or three-dimensional porous architectures. This aspect becomes important, especially, in applications where mass transport-related […]
Accessing Extreme Spatiotemporal Localization of High-Power Laser Radiation through Transformation Optics and Scalar Wave Equations
Tightly focused ultrashort laser pulses are used in many applications including laser machining of materials, eye surgery, and nanoprocessing of biological cells. Also, the high intensities that can be achieved under such conditions enable warm dense matter studies and the observation of exciting new material states. Simulations though of such extreme systems proved to be […]
Enhanced terahertz wave emission from air-plasma tailored by abruptly autofocusing laser beams
Laser-plasma based THz emitters offer broad radiation bandwidth, high output pulse energy and immunity to high power damage. Various excitation wavelengths and gases were explored to seek for a stronger THz wave emission from laser-induced plasmas, whereas few attempts were made for this purpose with artificially modulated exotic wave packets. We demonstrate that abruptly autofocusing […]
Size Effects of Platinum Nanoparticles in the Photocatalytic Hydrogen Production Over 3D Mesoporous Networks of CdS and Pt Nanojunctions
3D mesoporous architectures of CdS and Pt nanocrystals are demonstrated as highly effective catalysts for the hydrogen evolution reaction (HER). Photocatalytic measurements coupled with spectroscopic studies suggest that deposition of ultrasmall Pt nanoparticles enhances the H2-production activity because of variations in the band-edge positions and electron donor density of CdS nanocrystals. More information can be […]
A sub-femtojoule electrical spin-switch based on optically trapped polariton condensates
Practical challenges to extrapolating Moore’s law favour alternatives to electrons as information carriers. Two promising candidates are spin-based and all-optical architectures, the former offering lower energy consumption, the latter superior signal transfer down to the level of chip-interconnects. Polaritons—spinor quasi-particles composed of semiconductor excitons and microcavity photons—directly couple exciton spins and photon polarizations, combining the […]